The hemoglobin system of the brown moray Gymnothorax unicolor: structure/function relationships

Eur J Biochem. 2001 Jul;268(14):4104-11. doi: 10.1046/j.1432-1327.2001.02333.x.


The Gymnothorax unicolor hemoglobin system is characterized by two components, called cathodic and anodic on the basis of their isoelectric point, which were separated by ion-exchange chromatography. The oxygen-binding properties of the purified components were studied in the absence and presence of chloride and/or GTP or ATP in the pH range 6.5-8.0. Stripped cathodic hemoglobin showed a small reverse Bohr effect, high oxygen affinity, and low co-operativity; the addition of chloride only caused a small decrease in oxygen affinity. In the presence of GTP or ATP, the oxygen affinity was dramatically reduced, the co-operativity increased, and the reverse Bohr effect abolished. Stripped anodic hemoglobin is characterized by both low oxygen affinity and co-operativity, and displayed a normal Bohr effect; the addition of chloride increased co-operativity, whereas ATP and GTP significantly modulated oxygen affinity at acidic pH values, enhancing the Bohr effect and giving rise to the Root effect. The complete amino-acid sequences of the alpha and beta chains of both hemoglobins were established; the molecular basis of the functional properties of the hemoglobins is discussed in the light of the primary structure and compared with those of other fish hemoglobins.

MeSH terms

  • Allosteric Regulation
  • Amino Acid Sequence
  • Animals
  • Fishes*
  • Hemoglobins / chemistry
  • Hemoglobins / physiology*
  • Molecular Sequence Data
  • Oxygen / metabolism
  • Phosphates / metabolism
  • Sequence Homology, Amino Acid
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization


  • Hemoglobins
  • Phosphates
  • Oxygen